Tag Archives: material

Post navigation

In our urban environment we see numerous examples of open spaces with hard paving all over them. One of the reasons for this is our insatiable hunger for parking. The earth in our cities is starved of air and water — sacrificed at the altar of our rubber-shod tin cans.

“Ah”, but I hear you say, “we really do need that parking space!”.

Of course, if our city fathers were more enlightened and aimed for better public transportation instead of caving in to the cult of the car, we wouldn’t have reached this impasse in the first place. However, this page is not a rant about ineffective urban planning but about the effects of indiscriminate paving and what we can do about it.

When we pave over open spaces, a number of things happen.

The Water Table Drops Dramatically

This one is pretty obvious and hardly needs an explanation. If the ground is paved, there is no way that any more than a tiny fraction of rainwater will ever reach the soil. In Bombay, there was a time when one could dig a well and hit water not far below the surface. These days, the only reliable wells are the ones that adjoin large green spaces — like the maidans for example.

Other cities are not so lucky and those who live where borewells are common will tell you that the wells need to be dug deeper every year. The water they reach is also an increasingly fickle seam. The demand on the groundwater is constantly on the rise but all that paving never allows it to get recharged.

Egress of Saline Water in Coastal Areas

Freshwater is lighter than saline water

Saltwater is denser than freshwater and forces its way inland below the latter. If the (fresh) water table drops, the boundary between them is pushed deeper inland. Salinity in the soil is not merely bad for plant life but also for construction.

Trees Find it Difficult to Survive

For plants — and especially trees — paving is doubly detrimental. Not only is there very little water in the soil to help them grow but their roots are also unable to breathe. As a result, the trees develop a weak rooting system; it is no wonder so many of them topple over during the monsoons. That many of the avenue trees in our cities are fast-growing exotics, doesn’t help very much either.

Drainage Systems are Overwhelmed

When it rains in an urban area that is excessively paved, the runoff has to go somewhere! That somewhere, is the storm-water system which is frequently unable to cope. This leads to the all-too-familiar floods we see every year.

At best, flooding is an inconvenience but, as the last few years have shown us, it can also be deadly. Corrupt builders, politicians, and bureaucrats are responsible for the rampant encroachment on natural drainage channels in many of our cities. This results in the kind of devastation and loss of life we saw in Bombay (2005), and Madras (2015).

No doubt, in both cases there had been uncommonly heavy rainfall. We must remember, however, that climate change is causing an increased frequency of such extreme events, so it would be foolish to brush them aside as a freak events.

Worsening of the Urban Heat Island Effect

Paving is one of the major factors leading to the heat island effect — that phenomenon where an urban area is significantly hotter than its surroundings.

Unlike soil which cools off rapidly when the sun goes down, paving retains heat for longer and then emits it slowly through the night. One of the only ways to reduce this effect is to increase the area under plantation (including on roof terraces). However, as we have seen earlier, that is rather hard to do, when everything has been paved over. It’s a bit of a vicious cycle.

What We Need to do

Of course the very best thing to do is to avoid paving as far as possible. However, there are many situations when we really have no choice. At such times, the least we can do is to use materials and systems to mitigate the problems we cause.

Pervious Concrete Paving

This is a type of concrete where the fine aggregate (sand) is missing so that the concrete becomes porous enough for water to percolate through. This means, of course, that it is not as solid as other concretes and cannot sustain the same heavy-duty usage. On the other hand, it is perfectly usable in areas where traffic density is low or, for example, in parking lots.

Some cities like Portland, Oregon in the USA have experimented quite extensively with permeable paving. Unfortunately, there is little sign of anything even remotely close being done here.

Perforated Paving Block or Grass Paver

These are easily available here but not as commonly used as I wish they were. They are easy to lay and, to my eye, they make a space look much nicer than if were completely covered with a hard surface.

Permeability is excellent but, like porous concrete, it can only be used for low-traffic areas or parking lots.

Tree Guards

If all else fails — and even if not, it is wise to have tree guards which allow the soil around the roots to breathe. This is something that is conspicuously lacking in our cities.Instead, we see a low brick wall made as close to the trunk as possible. Apart from being undersized and ugly, these are also tripping hazards for pedestrians.

It would be so simple, instead, to embed a cast iron tree guard that is level with the pavement. If the city authorities feel that the iron will be pilfered, they can do something similar in ferro-crete. It won’t look half as nice but at least it will be effective.

Green Roofs

While a green roof can’t do very much for the surface runoff and the storm-water systems, it can certainly be help reduce the urban heat island effect.

Planted roofs haven’t caught on too well here as yet. That will not change until waterproofing systems become much more reliable. People who have running battles with monsoon leakage are unlikely to tempt fate.

Conclusion

The situation is far from ideal but it isn’t a lost cause just yet. Given enough awareness and pressure from the general public, things can improve. Organisations like depave, for example, have done this very effectively. They have not only raised awareness in Portland but have even forced the local government to reverse past mistakes.

Maybe it’s time to start something like that in all our cities here as well.

Just received a call from a gentleman who wanted to develop 9 acres of land at Nasrapur village in Karjat, very close to some of the bungalows I’ve done and am doing there. That sounded interesting, naturally.

Unfortunately he wanted to make houses entirely and exclusively out of prefab steel. Never mind that they would not be environmentally sustainable and, therefore, contrary of the kind of work I do; never mind, even, that they might look like factory sheds! Someone had obviously convinced him that this was the way to go.

I said that I could not take up a project if I felt it was ecologically damaging and urged him to at least consider other options. He was closed to such crackpot ideas but very understanding about my foolishness. His words were, “Yes, of course, everyone has their… their own…” and then his voice trailed off.

Sometimes, it’s better to lose a project before you even have it in hand.

Just in case I’ve got you visualising rodents scurrying about where they’re not wanted, ease your mind; the rat trap bond I’m talking about is simply a method of laying bricks when building a wall. It’s similar to the common “Flemish” bond but instead of putting the bricks on their face, they are placed on their edges. This leads to cost savings because less bricks and cement are needed which, in turn, reduces the embodied energy of the wall.

Bricks are laid on edge to create an air gap between two layers

Laurie Baker took every opportunity to try and make people realise the value of this method but, by and large, the 20-25% saving in brick doesn’t seem to have been appealing enough. The rat trap method of construction was popular in England until the start of the 20th century but sustained lobbying by the brick-making industry convinced people that that it was not strong enough to build load-bearing walls.

That is rubbish of course; it’s strong enough for one and two storey buildings as has been proven over and over again by Laurie Baker’s lasting work. But masons too are not usually happy about adopting this system and come up with all sorts of excuses to try and avoid it. I have to admit that, till date, I have not pushed hard enough against their inertia but now I’ve just got one more reason to do so.

For the ShKo bungalow at Karjat, I plan to use the rat trap walls and wanted to know just how much difference they would make thermally. Nobody seems to have done a calculation of the difference — at least there was none that I could find. So, armed with some data from thermal calc and the energy evaluation component of ArchiCAD, I tried to do just that.

Taking just a simple 3m x 3m structure with no openings, I ran a calculation for both types of wall. Result: average U-value of the structure’s outer shell dropped about 15% compared to conventional walls and the energy required for cooling also fell by about 8%. The difference was exaggerated because the model had good roof overhangs to shade the walls.

Still, when you think about it, 8% is nothing to scoff at. In addition, the embodied energy is reduced quite dramatically and, of course, Laurie Baker’s original reason for using the rat-trap bond still stands — the wall is simply cheaper to build.

Now, I just have to go and steam-roll the masons into learning a new technique.

Why Asbestos is Poison

Asbestos reinforced cement sheets make for a cheap and effective roofing system that minimises the amount of steel used to erect it. Asbestos itself is a naturally occurring mineral found in many places and the fibre is known to cause Lung Cancer and Asbestosis – a disease that is painfully debilitating and often leads to death.

Because the material has been used so extensively and for so long, the asbestos cement sheet industry has become rich, powerful and entrenched. Apologists for these companies blow smoke in your eyes and have (so far) prevented the material from being banned here – unlike in some other nations.

The companies, at least in India, have two standard arguments:

The fibres used here are not blue asbestos (crocidolite), but white asbestos (chrysotile) which is “safer”. That’s like saying they’ll kill you with regular dynamite instead of blowing you to bits with semtex – and even this argument is probably flawed.Until the 1950s, scientists – while admitting the health hazards of asbestos – made no distinction between the types or their ability to cause diseases. When in 1960, it was found by one Dr. J.C. Wagner in South Africa that blue asbestos caused malignant mesothelioma (cancer of the linings of the lungs, chest and abdomen), it caused a furore in the industry there.Interestingly, since it was chrysotile that was the major asbestos of commerce and used in the U.K. and U.S., industry seized blue asbestos as the culprit, declaring that white asbestos has not been similarly implicated and so it is safe. Full story

Manufacturers will also tell you that once the asbestos fibre is locked into a sheet, it’s perfectly safe. That may well be true, but when a sheet is cut or drilled on site – and it almost always is – some fibres are bound to be released. Even if we discount the risk to the end-user and grant that the exposure may not be sufficient to cause any health problems, what about the poor labourer who mines the material? It gets into his lungs every day of his working life and a large part is carried home on his person and his clothing, thereby exposing his family to the very same risks. I’m sorry, but that is just not acceptable. And if anyone tries to say that there are safety standards, I’d ask them which world they’re living in. Safety standards in this country are conspicuous by their absence.Although more than 40 countries – most with far better safety standards – have already banned all kinds of asbestos, our politicians still try to question the rationale. After all, life is cheap in a country of 1 billion people and lobbying by large companies always works. I’m sorry if I sound cynical but there are just too many many horror stories to read about.

So what are the Alternatives?

So far, the only non-asbestos corrugated sheets I’ve come across are “Hi-Tech” (that’s the cheesy brand name) made by Everest Industries. They use polypropylene fibres instead to bind the cement and are available as plain grey sheets or in three or four pre-coated colours.

Everest Hi-Tech is an ideal roofing and cladding material for factories and warehouses in a variety of industries viz. Food, Pharmaceuticals, Textile, Engineering, Chemical, Automobiles, Metallurgical etc. It is particularly suitable where the factory/ warehouse need to conform to globally accepted and export compliant construction norms.

Everest also makes asbestos products by the way so it may be a deterrent for some but I’d rather encourage the alternative material because unless enough demand is created, the manufacturers will never give up on asbestos. So far, they don’t sell the sheets retail but do so only on a project basis from their factory at Coimbatore; if your quantity is small, it’ll work out slightly expensive. I’ve yet to come across other companies making similar products but hope they do in the near future.

More

If you are the manufacturer/dealer of any product that you feel is appropriate for this page, please fill this form stating clearly what exactly makes your product green/sustainable.

Please note that Greenwashing will not get you anywhere and inclusion of the product is not guaranteed and is entirely at our discretion.

Challenging a Mindset

I have often found that builders, architects and indeed, clients, want to make even the smallest structures using reinforced concrete cement – or RCC. This is a mixture of cement, sand and aggregate (stone chips of gravel) that is cast around a framework of reinforcing steel rods. Once the skeletal framework of concrete beams and columns is in place, the gaps are filled in with bricks for the walls. But bricks are perfectly capable of taking the load of low-rise structures by themselves so, why have the RCC at all?

Unfortunately, many people have become obsessed with using RCC because it holds the promise of a more stable construction – a notion that is not often true. To be sure, if you’re talking about a multi-storey building, RCC is the cheapest way to go. But if you’re making just a one or two storey house, load-bearing bricks will do just fine. To illustrate, at the time of writing this, I’m living in a four storey load-bearing building that was constructed in c.1900. It’s obviously seen earthquakes, storms and floods and doesn’t seem the worse for the wear. In contrast, other buildings in my neighbourhood – those built using RCC – seem to need extensive repairs every 7-10 years.

Slipshod Work

Even discounting the cement-shortage years of the 1970s, concrete structures in our country are, by and large, badly made. In our climate, the steel often starts to rust even
before the casting begins and, the concrete cover is not enough to protect it from further corrosion in humid areas. Worst of all, the columns and beams are, more often than not, found to be honeycombed once the formwork is removed (this is quickly patched up but the structure remains inherently weak).

Finally, there is a widespread consensus among both, literate contractors and illiterate workers that chiselling away some concrete to embed, say, electrical conduits is perfectly allright as long as nothing collapses in the next twenty four hours. Others who consider themselves very safety concious will make sure they don’t actually cut the steel in their endeavours. This would be very funny if it wasn’t so dangerous.

Unfriendly to Nature

Apart from all this, by its very composition, RCC is a wasteful material. It uses large amounts of cement which, in turn, require huge amounts of fossil fuel to produce. The structure becomes heavy and, a fair portion of its cross-section goes in supporting its own weight. Finally, once the life of the building is over, it is almost impossible to extract the steel (also an energy-intensive material) for any meaningful purpose.

Reducing the Ecological Impact

There are many ways in which RCC can be made less wasteful — using filler slabs, for instance. But doing that requires a little extra effort and there is a general apathy that prevents even this simple method from being used. I once had the opportunity to climb onto a 100-year old lime-concrete vaulted roof that was undergoing repair. I was amazed to see how the builders had used ordinary terracotta pots to lighten the structure.

Another alternative which can be used for select elements is ferrocement or ferrocrete. This uses thinner sections with minimal steel – often just chicken mesh – but relies on the element’s geometry to provide structural stability. For example a roof slab can be folded like a paper fan or, a staircase which is an ideal candidate for ferrocement will use less than 25% of the material compared to a traditional concrete one. Not many contractors know how to do it correctly though, which leads them to avoid taking up such work. That, in turn, makes it a rare thing which makes everybody very hesitant. It’s a vicious cycle.

And of course, the easiest way to avoid concrete is in low-rise structures which usually don’t require it in the first place.

One of the first principles of sustainable and environmentally friendly architecture is to reduce the embodied energy of the materials used in construction. Embodied energy is the sum of all energy inputs–for manufacturing, all transportation, human resources etc–that are needed to make a product. Transportation plays a major role here so, if a material can be sourced locally, it can reduce the embodied energy (and carbon footprint) quite substantially.

With services like Google Maps available to us, it has become very easy to get data like distance from source to site

Mahatma Gandhi–an instinctive environmentalist if ever there was one–exhorted people to build with materials that were available within a 50km radius. His reasoning may have had little to do with a scientific knowledge of embodied energy and more to do with his lifelong devotion to the concept of localisation and decentralisation. Regardless, if we keep the 50km limit in mind for most materials, we can prevent the burning of a lot of fossil fuel.

An additional advantage is that, as transportation costs are minimal for local materials, they are also usually more affordable than something that comes from a great distance. Besides, if you’re planning on using local labour then, their familiarity with it leads to a sturdier and better finished project.

However, we must always weigh our options with an open mind. As an example, for corrugated roofing, I refuse to use asbestos sheets on principle. For a project outside Mumbai, I considered getting a non-asbestos alternative from Coimbatore. However, we eventually settled on a flat sheet made from bagasse by a Pune company even though it needed a heavier steel framework to support. Why was that?

The corrugated roofing system would have had less embodied energy even after transportation but, the sheets themselves could only be bought in bulk from the manufacturer so, if the project ever needed just a single extra sheet at any stage, we’d have to call for an entire truck — even if it was almost empty. That, in the end, tipped the scales in favour of the more readily available Ecoboard.

Flyash bricks can be made to look like traditional bricks if you add a little red-oxide in the mix. This is useful if you want to keep the wall un-plastered like we did for the RaBV Bungalow.

Another time, for the [RaBV] bungalow, the clients were willing to pay the extra transportation cost to bring in flyash bricks, from Wada in Thane district, to Karjat — a distance of approximately 100km. Apart from the fact that manufacture of clay bricks leads to the loss of precious topsoil, the overall embodied energy is substantially lower despite the fuel burnt for carrying them over the distance. Here is the basic calculation:

So, as you can see, there are no hard and fast rules when it comes to distance. Each case has to be looked at individually and assessed on merit. We also don’t always have ideal situations but we must, at the very least, aim to minimise the embodied energy of our structures.

Apart from materials derived from waste or those that are recycled, we also have the option to use materials that are naturally renewed. Examples of this are plantation timbers (which do come with their own set of problems).

Plantation Woods

It is almost impossible to be sure that the wood we get in India comes from sustainable plantations. Most vendors haven’t a clue and the smart ones will see your interest and have not the slightest hesitation in assuring you that the wood you’re looking at has never been in a natural forest in its life. Our Sal [Shorea robusta] comes from South East Asia and our Teak [Tectona grandis] comes from Western Africa but that’s as far as our information goes.

We do get pine, cedar and hemlock from sustainable forests in Canada etc. but these are soft woods that our local carpenters are unfamiliar with and, when they mess up, they quickly blame the wood.

Recently, I came across a supplier of wood who says his products are all certified by the Forestry Stewardship Council and I’d like to see more local suppliers do the same – after all, if it’s been certified outside the country, then the material too has been transported a very long way from its source!

Bamboo

This is a prime example of a renewable resource – seeing as it is the fastest growing plant in the world. It is also versatile and can be converted into all sorts of panel products like plywood, flooring and even fabric. It isn’t always easy, but it may be prudent to determine the source of the raw material to make sure it’s from a sustainable plantation and not from a forest. Bamboo is considered by many to be our only hope for the future.

There are innumerable resources for Bamboo on the internet.

Oriented Strand Board [OSB]

Unlike plywood that needs large logs to produce, OSB can make do with even thin ones from fast-growing plantation trees. It isn’t available in India but, hopefully, will be here in a few years…

I’ve been given to understand that some dealers get hold of waste chipboard from packaging in shipping containers, which they then sell as OSB. It’s fantastic that they’re recycling the chipboard; I’m just making you aware that it’s not the same as OSB.

There are numerous by-products, of some process or industry, that are considered waste and and it only takes a little imagination to recycle them to be of use for building and construction.

Flyash

As a fine residue from coal-fired thermal power plants, flyash is a serious health hazard if released into the atmosphere. These days, it is filtered out before the flue gasses are released and then dumped in “ponds”. But what’s to be done with all this flyash? For one thing, we can make good use of it!

Flyash is a pozzolan — it has cementatious properties. While it can’t be used as an alternative to cement, it can act as a good filler for concrete which turns out stronger – and uses less water – than that made with cement alone.

In India, it is usually used to manufacture bricks that are stronger than the traditional terracotta ones; they use less mortar to lay, absorb less water and don’t require to be fired in a kiln, thereby not adding to the pollution in the atmosphere.

For the [RaBV] Bungalow in Karjat, we used flyash bricks and adding red iron-oxide to the mix. The resultant colour was a pale terracotta that is quite pleasant. Next time, I’ll try getting yellow bricks with yellow oxide. The manufacturer’s factory is near Virar, North Bombay (Mumbai), but the quality of the last batch of bricks we received deters me from recommending him.

Bagasse

This is the waste from sugar cane once the sugar is extracted. It can be used to make particle boards or other fibre-boards. Unlike wood-based products, it isn’t affected by borers. One company, that I know of, which uses agricultural waste products like cotton stalks or bagasse is Ecoboard Industries based in Pune.

Rubber Wood

Rubber wood is a by-product of rubber plantations that are found over a large part of Southern India. Left to itself, the wood rapidly deteriorates and discolours but, if treated properly, can be used for a variety of purposes – especially in furniture. It has a pale golden yellow colour when given a natural polish. One drawback that needs to be taken into account is the extent of its response to moisture. Since the wood is kiln dried, the moisture content is low when you receive the material but it can react quite alarmingly during the monsoon.

Coconut Plyboard

This is a product that, I have to admit, I haven’t used. ! I’ve seen the samples however and what’s so appealing about it – apart from the fact that it’s made from waste coconut husk – is the wonderful dark natural colour.

The company that manufacturers it, Natura Fibretech Pvt. Ltd, is in Bangalore, so getting a small quantity to Bombay works out much too expensive.

Construction Debris

This is not something that can be used on a regular basis or in large quantities but, when one is doing a plinth backfill, it makes sense to use debris from some other construction. Every little bit helps. The tragedy of places like Bombay is that this debris is being systematically dumped by unscrupulous builders into our vanishing mangroves.

More

If you are the manufacturer/dealer of any product that you feel is appropriate for this page, please fill this form stating clearly what exactly makes your product green/sustainable.

Please note that Greenwashing will not get you anywhere and inclusion of the product is not guaranteed and is entirely at our discretion.

It may sound old-fashioned and Gandhian, but if building materials can be sourced from the local area rather than from halfway across the country, you are not just saving on fossil fuel used in transportation but, most likely choosing something that is appropriate for the local climatic conditions.Continue Reading →

What is Sustainability?

“Nature has enough for everybody’s need; not for everybody’s greed.”
– Mahatma Gandhi

Quoting Mohandas Karamchand Gandhi may no longer be fashionable but these words are more relevant today than they’ve ever been.

Every material used in construction comes, eventually, from the earth. For any architect who cares about nature, that is a predicament to be faced every day. I know it is unrealistic to halt the production or extraction of such materials but we should, at the very least, try and minimise their usage.

A simple example: small structures in India are often built with reinforced cement concrete frames when ordinary load-bearing brickwork (which is about 25% cheaper by the way) would be more than satisfactory.

Nature-friendly Architecture & Design

Nature has an enormous ability to repair herself but when we exceed her capacity to do so, this cycle of restoration and renewal is broken.

Sustainable architecture and design takes into consideration all aspects of construction that affect the environment.

There are many factors that go into making a building nature-friendly:

A large chunk of a construction’s carbon footprint is determined by the materials used. For small structures, reinforced concrete (RCC) framing is environmentally expensive and thoroughly unnecessary to boot! I’ve found that load-bearing work usually does a better job.Continue Reading →

Better design is not just about aesthetics. It holistically considers architectural design, landscape & plantation, sustainable systems & climatic conditions,. A well designed construction has minimal negative impact on the site and its surroundings.Continue Reading →

During its life cycle, a building needs an enormous amount of energy for lighting, heating & cooling. A design that makes good use of naturally occurring sunlight & prevailing breezes goes a long way in saving associated costs.Continue Reading →

Economists have pointed out that future wars will be over water which makes this the most important factor in my estimation. Saving, harvesting and recycling water is far easier than it is made out to be and you often don’t need an expert to get it working.Continue Reading →

Disposal of solid waste might not be an architect’s area of expertise but we can play a proactive role by designing for composting pits etc.
[under construction]

Impediments

If you compare apples to oranges, you will invariably draw the wrong conclusion.

The biggest deterrent to making clients accept sustainable solutions is, usually, perceived cost. That’s because they almost always compare apples with oranges. For example, if a solar heating system is installed for a project, it will naturally raise the initial cost but, if you calculate how much it saves in the medium to long term, you will find that it doesn’t make sense not to fit it. Essentially, green buildings cost less in the long term.

Even as far as basic construction is concerned, green building costs can be made lower than for typical structures. This was amply demonstrated while building Kaya Kalp where, locally available, low-tech materials and labour were used.

Post navigation

You are Here

Follow

Get Email Updates

Featured Articles

The incandescent bulb is the most common - and one of the more wasteful - ways of lighting a space. Today we have many efficient light sources ranging from fluorescent tubes to CFLs that retro-fit into incandescent holders. Also, Light Emitting Diodes - LEDs are rapidly reaching a level of affordability.Continue Reading …

About

Vistasp Mehta is a Mumbai-based architect working on sustainable design, with a special emphasis on energy and water conservation. Other obsessions include art, history, technology, wildlife and photography.